Alloy and method of making and casting same



July 14, 1925. I H 1,545,705

w. H. SMITH ET AL- ALLOY AND METHOD OF MAKING AND CASTING SAME FiledAugf22, 1921 INVENTORS.

William H.5m'urh Patented July 14, 1925.

UNIT ST TES PATENT OFFICE.

WILLIAM E. SMITH, OF EAST CLEVELAND, AND CHARLES CAMPBELL,- O l' CLEVE-LAND, OHIO, ASSIGNORS 1'0 THE PIONEER LAND, OHIO, A CORPORATION 01 DELAWALLOY IiRODUCTS COMPANY, 01' CLEVE- ALLOY, nun man or mxme AND oasrmesum Application filed August 22, 1921. Serial No. 484,055.

To all whom it may concern: Y

Be it known that we, WILLIAM H. SMITH- Thls invention relates toapparatus for technical chemical operations such as are encountered inacid works, alkali works, oil refineries, dye works, steel works,general chemical manufacturing, electrolytic, works and numerousotherplaces in the arts where valves, cocks, pipes, fittings, pumps,containers, evaporators, condensers, concentrators, mixing machines andother devices are employed. The ultimate object of the invention is theprovision of an intrinsically inexpensive metal or alloy for thesepurposes which shall be sufficiently resistant to corrosion to exhibit along life, which shall be sufiiciently strong mechanically to withstandthe ordinary usage to which such devices are subjected, and which shallbe easily machined, forged, or otherwise fabricated. No material havingall these qualities has ever come into commercial use, althoughmaterials possessing some of these qualities have long been known. Forexample, platinum is nearly perfect excepting vfor its cost: glass andporcelain having the necessary chemical resistivity but are mechanicallyfragile and also difficult to Work. Numberless alloys exist having thenecessary strength and workability but deficient in chemicalresistivity.

It has long been suspected that some alloy containing essentiallychromium and one or more iron group metals could be employed for thispurpose, but no one has heretofore produced either a composition or amode of handling it which resulted in a product of the highest utilityfrom the chemical standpoint, the chief difficulty being that anadmixture of any material amount of carbon renders such an alloyunworkably hard, physically brittle, and'j chemically non-resist- Ioperation to be conducted away from it.

ant. However, ods of producing such alloys have always resulted,at'least when performedon a commercial scale, in the abso tion of suchan amount of carbon asto ren er the product of verysmall value forchemical apparatusregardless of whether an open hearth furnace, cruciblefurnace, or electric furnace be employed. A bath containing any materialamount of molten chromium will dissolve solid carbon from fuel orcrucible, carbon gas such as hydrocarbon or monoxide from combustionproducts, or volatilized carbon from an electric arc with equal avidity.Heretofore alloys containing more than about of chromium have beenconsidered practically unmanageable.

The immediate objects of this invention are the provision of a furnacecharge and a mode of mani ulation which shall result in a useful,low-car on, alloy, containing essentially the ingredients named, with orwithout other ingredients; the provision of a furnace charge containingthe essential substances in their chea able forms; the provision of afurnace charge and mode of manipulation such as shall facilitate thefusion and enable the at the lowest possible temperature; the provisionof a new and improved slag for alloys of this nature; while furtherobjects and advantages of the invention will appear as the descriptionproceeds.

In the drawings, Fig. 1, is a View showing the charge prior to melting,and Fig. 2 shows the same charge melted; Fig. 3 illustrates the mold,and Fig. 4 certain apparatus made of alloy.

It is necessary to employ an electric furnace and this of a type whereinall the electric terminals are located above the surface of the metalbath. The hearth of the furnace is preferably made of magnesite and allcarbon or carbonaceous matter is kept We preferably mix it with st andmost avail' between this previous niethhydrochloric acid instead of theusual mo-' I lasses, and mold the mixture into the desired form,afterwards sintering the hearth in any mode customary in electricfurnace practlce, This operation serves to contaminate the ma esite witha certain 'amount of carbon which must now beremoved and this we effectas by introducing a small amount of low carbon iron scraptogether withlime and enough fluorspar to thin the slag. The furnace interior isthoroughly washed as man times as is necessary to cure chemicalresistivity.

Ferrochrome (.40% O.) 35. lbs.

Cr 24.86 C 0.14

Iron (.14% C.) 25. lbs.

Nickel (free from carbon) 30. lbs.

Ferro-molybdenum (1.% C.) 10. lbs.

Fe 4.9 Mo 5. C 0.1

100. lbs.

In terms of totals this charge contains approximately: chromium 25, iron40, nickel 30, molybdenum 5, carbon .28.

Inasmuch as the iron content of ferrochrome and ferro-molybdenum isquite variable it is impossible to predict a charge with accuracy interms of these ingredients, although considerable latitude in ultimatecomposition is permissible. In general we preferably adjust theproportions of these ingredients in accordance with their comosition soas to secure a charge lying substantially within the range indicated bythe following:

A B C D E F G H Chromium 2o 20 25 25 30 30 35 Nickel (or 00- balt) 35 4030 40 25 30 30 40 Iron 40 35 40 30 40 35 30 22 Molybdenum. 5 5 5 5 5 5 58 Carbon below about .3 .3 .3 .3 3 .25 .25 .2

The hi her the chromium and the lower the nickel the less the carboncontent must be in order to avoid brittleness and low chemicalresistivity.

We do not restrict ourselves to the charge s ecified as we may omit thenickel entirely, replacing it with either cobalt or iron, and may varythe chromium content through a wide range. Indeed in the absence ofnickel (or cobalt) an increased amount of chromium is necessary to se-We have used Silica and its compounds are excluded with success a chargecontaining approxi- A mately:

Chromium 50 Iron 44-% Molybdenum 5 resulting in an alloy ofapproximately: Chromium 45-47 Iron -48 Molybdenum 5 This alloy isextremely diflicult to make owlngto its great avidity for carbon, and tothe necessity for keeping the carbon below .2% and preferably evenlower. This requirement necessitates the use of a purer grade offerrochrome which increases its expense disproportionately, and themelting point is inconveniently high. The use of nickel avoids all thesedrawbacks, yet the termary alloy just mentioned is very satisfactory inuse and can be made successfully by the process herein described.

The iron is thrown or piled in the center of the hearth as shown at AinFig. 1, the

nickel (when used) around it, as shown at at with the electrodes andcovered with a mixture of lime and uorspar D, some three or four inchesdee This lime and fluorspar must be of goo quality, mixed thoroughlytogether in the proportion of about 80% to of lime and the balancefluorspar, the two being preferably ound together to a condition ofinsepara le interminglig;

t because of the danger of reduction by chromium and the certainty thatthe meltin point of the slag would be unduly decrease The molybdenum isnot added until the last. Indeed it is possible' and highly satisfactoryto add on y the iron at first and follow with the other ingredients butthe the ferrochrome around that, ,as' shown mode described is quickerand more con venient.

The furnace is" then startedin the usual manner, and as soon as the ironhas melted the heat thereof slowly causes the ferrochrome to dissolvetherein and the slag to soften and flow thereover, so that the arc' thesame will absorb carbon from the arc,

but the iron and nickel will not do so. When the entire charge has beenmelted and incorporated thorou hly together, a suitable deoxidizer isadde and the molybdenum or ferro-molybdenum or other added substance isincorporated, after which the alloy is This covering of the C, that lastbeing kept out of contact llt)

